expression: add max_allowed_packet check in concat/concat_ws

[amyangfei]

What problem does this PR solve?

Return NULL and a warning when the result of function concat or concat_ws exceeds max_allowed_packet. ref: #7153

After this PR,

mysql> select @@global.max_allowed_packet;
+-----------------------------+
| @@global.max_allowed_packet |
+-----------------------------+
| 1024                        |
+-----------------------------+
1 row in set (0.00 sec)

mysql> select concat (repeat('a', 10), 'b');
+-------------------------------+
| concat (repeat('a', 10), 'b') |
+-------------------------------+
| aaaaaaaaaab                   |
+-------------------------------+
1 row in set (0.00 sec)

mysql> select concat (repeat('a', 1024), 'b');
+---------------------------------+
| concat (repeat('a', 1024), 'b') |
+---------------------------------+
| NULL                            |
+---------------------------------+
1 row in set, 1 warning (0.01 sec)

mysql> show warnings;
+---------+------+--------------------------------------------------------------------------+
| Level   | Code | Message                                                                  |
+---------+------+--------------------------------------------------------------------------+
| Warning | 1301 | Result of concat() was larger than max_allowed_packet (1024) - truncated |
+---------+------+--------------------------------------------------------------------------+
1 row in set (0.00 sec)

What is changed and how it works?

add max_allowed_packet check during evalString in builtinConcatWSSig and builtinConcatSig

Check List

Tests

• Unit test
• Integration test

Related changes

• Need to cherry-pick to the release branch

[codecov]

Codecov Report

Merging #11137 into master will decrease coverage by 0.4173%.
The diff coverage is 81.25%.

@@               Coverage Diff               @@
##            master     #11137        +/-   ##
===============================================
- Coverage   81.677%   81.2596%   -0.4174%     
===============================================
  Files          423        423                
  Lines        91699      90073      -1626     
===============================================
- Hits         74897      73193      -1704     
- Misses       11494      11577        +83     
+ Partials      5308       5303         -5

[amyangfei]

/run-all-tests

[amyangfei]

is this issue #7153 still needed to complete, PTAL @zz-jason

[amyangfei]

/run-all-tests

[zz-jason]

LGTM

[SunRunAway]

/run-all-tests

[SunRunAway]

LGTM

[SunRunAway]

/run-all-tests

[SunRunAway]

Codecov is decreased but I have no idea how to fix it. Maybe we should consider fixing #11269 to solve this.

[sre-bot]

It seems that, not for sure, we failed to cherry-pick this commit to release-2.1. Please comment '/run-cherry-picker' to try to trigger the cherry-picker if we did fail to cherry-pick this commit before. @amyangfei PTAL.

[XuHuaiyu]

/run-cherry-picker

[sre-bot]

cherry pick to release-2.1 in PR #16175